Basic terminologies:
Vertices,edges,undirected and directed graph,cyclic & acyclic graph,degree indegree & outdegree and weights. In an undirected graph, the sum of degrees of all vertices is double the vertices (We consider degree=indegree=outdegree in an undirected graph).
Graph representation in C++
Let us say there are n nodes and m edges. There are two ways to represent a graph
Adjacency matrix adj[i][j] represents there is an edge from node i to j. int n, m; cin >> n >> m;
// declare the adjacent matrix int adj[n+1][n+1];
// take edges as input for(int i = 0;i<m;i++) { int u, v; cin >> u >> v; adj[u][v] = 1; adj[v][u] = 1; } 2.